[R] seq

Roger Bivand Roger.Bivand at nhh.no
Fri Sep 3 13:41:56 CEST 2004


On Fri, 3 Sep 2004, Henric Nilsson wrote:

> Hi everyone,
> 
> I've tried the below on R 1.9.1 and the 2004-08-30 builds of R 1.9.1 
> Patched and R 2.0.0 on Windows 2000, and the results are consistent.
> 
>  > seq(0.5, 0, by = -0.1)
> [1] 0.5 0.4 0.3 0.2 0.1 0.0
> 
>  > seq(0.7, 0, by = -0.1)
> [1]  7.000000e-01  6.000000e-01  5.000000e-01  4.000000e-01  3.000000e-01 
> 2.000000e-01  1.000000e-01 -1.110223e-16
> 
> Is this really the intended behaviour? I ended up using

Well, you are using a floating point representation in a digital computer, 
so I don't think you should be surprised. Note that the internal 
representation is also modified by the print() functions, so what you see 
when an object is printed is not always exactly what is inside the object.

> 
>  > seq(0.7, 0, length = 8)
> [1] 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0
> 
> which does what I want.
> 
> //Henric
> 
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-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Breiviksveien 40, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 93 93
e-mail: Roger.Bivand at nhh.no




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